#include<stdio.h>
main()
{
	int m,a;
	scanf("%d",&a);
	m=a/10;
	switch(m)
	{
		case 9:printf("A");break;
		case 8:printf("B");break;
		case 7:printf("C");break;
		case 6:printf(" D");break;
		default:printf("E");break;
		
	}
}
